Dear Gholamreza: my country, Venezuela, is endowded with many gold deposits, located mainly in the greenstone belts of the Pastora-Mazzaruni Province, in the SE of the country. And in every occasion they are related to quartz veins or pyritic metalavas, where the gold is invisible, being as micrometric inclusions in the sulfide. Of course, the most valuable deposits occur in alluvial, colluvial and, sometimes, elluvial deposits, were informal mining causes ecological disasters in the jungle. Regards, Sebastián.
Dear Gholamreza: in 1995 I was in a Geological excursion in Cuba, and island which is an arc/continent collision, and it is full of ophiolitic complexes, and a colleague there gave me some interesting samples, like a nodular chromite from the Moa Ophiolite, and one of serpentinite with gold veins in it! This is really and odd kind of gold mineralisation! Regards, Sebastián